The hepatocyte growth factor (HGF) receptor (c-Met or HGFR) receptor tyrosine kinase (RTK) has been shown in many human cancers to be involved in oncogenesis, tumor progression with enhanced cell motility and invasion, as well as metastasis (see, e.g., Ma, P. C., Maulik, G., Christensen, J. & Salgia, R. (2003b). Cancer Metastasis Rev, 22, 309-25; Maulik, G., Shrikhande, A., Kijima, T., Ma, P. C., Morrison, P. T. & Salgia, R. (2002b). Cytokine Growth Factor Rev, 13, 41-59). c-Met (HGFR) can be activated through overexpression or mutations in various human cancers including small cell lung cancer (SCLC) (Ma, P. C., Kijima, T., Maulik, G., Fox, E. A., Sattler, M., Griffin, J. D., Johnson, B. E. & Salgia, R. (2003a). Cancer Res, 63, 6272-6281).
c-Met is a receptor tyrosine kinase that is encoded by the Met proto-oncogene and transduces the biological effects of hepatocyte growth factor (HGF), which is also referred to as scatter factor (SF). Jiang et al., Crit. Rev. Oncol. Hematol. 29: 209-248 (1999). c-Met and HGF are expressed in numerous tissues, although their expression is normally confined predominantly to cells of epithelial and mesenchymal origin, respectively. c-Met and HGF are required for normal mammalian development and have been shown to be important in cell migration, cell proliferation and survival, morphogenic differentiation, and organization of 3-dimensional tubular structures (e.g., renal tubular cells, gland formation, etc.). In addition to its effects on epithelial cells, HGF/SF has been reported to be an angiogenic factor, and c-Met signaling in endothelial cells can induce many of the cellular responses necessary for angiogenesis (proliferation, motility, invasion).
The c-Met receptor has been shown to be expressed in a number of human cancers. c-Met and its ligand, HGF, have also been shown to be co-expressed at elevated levels in a variety of human cancers (particularly sarcomas). However, because the receptor and ligand are usually expressed by different cell types, c-Met signaling is most commonly regulated by tumor-stroma (tumor-host) interactions. Furthermore, c-Met gene amplification, mutation, and rearrangement have been observed in a subset of human cancers. Families with germline mutations that activate c-Met kinase are prone to multiple kidney tumors as well as tumors in other tissues. Numerous studies have correlated the expression of c-Met and/or HGF/SF with the state of disease progression of different types of cancer (including lung, colon, breast, prostate, liver, pancreas, brain, kidney, ovaries, stomach, skin, and bone cancers). Furthermore, the overexpression of c-Met or HGF have been shown to correlate with poor prognosis and disease outcome in a number of major human cancers including lung, liver, gastric, and breast. c-Met has also been directly implicated in cancers without a successful treatment regimen such as pancreatic cancer, glioma, and hepatocellular carcinoma.
A family of novel compounds have been discovered which exhibit c-Met modulating ability and have an ameliorating effect against disorders related to abnormal c-Met activity. c-Met is an attractive target from a clinical perspective because: 1) c-Met has been implicated in the growth and metastases of most types of cancer; 2) growth at the secondary site appears to be the rate-limiting step in metastasis; and 3) by the time of diagnosis, R is likely that the disease has already spread.
These observations suggest that c-Met kinase inhibitors would be an effective treatment for primary tumors that are driven by c-Met, but more importantly, would prevent disseminated micrometastases from growing into life-threatening metastases. Therefore, the utility of a c-Met inhibitor extends to preventative and adjuvant therapy settings. In addition, certain cancers (e.g., papillary renal cell carcinoma, some gastric and lung cancers) can be treated which are believed to be driven by c-Met mutation/genetic alteration and dependent on c-Met for growth and survival. These cancers are expected to be sensitive to treatment. Furthermore, various human cancers are the primary target indication for c-Met antagonists. These cancers include major cancers such as breast, lung, colorectal, prostate; as well as pancreatic cancer, glioma, liver cancer, gastric cancer, head and neck cancers, melanoma, renal cancer, leukemias, myeloma, and sarcomas. c-Met has been directly implicated in cancers such as pancreatic cancer, glioma, and hepatocellular carcinoma.
Accordingly, c-Met (HGFR) inhibitors and methods of using such inhibitors for the treatment of abnormal cell growth, such as cancer represent a substantial unmet medical need in the treatment of these and possibly other cancers.